1. Field of the Invention
The present invention relates to a field effect transistor in which a semiconductor substrate of a first conductivity has a source zone and a drain zone of the opposite conductivity spaced apart therein and a surface channel in an area between the source and drain zones which adjoins the surface of the semiconductor substrate and which has the second type of conductivity, and a gate electrode arranged over the surface channel.
2. Description of the Prior Art
In solid state electronics, various components are known which have a current-voltage characteristic which include regions of negative, differential resistance. Components of this type are, for example, tunnel-diodes, Gunn elements and IMPATT diodes. Another component having a negative, differential resistance is the Cryosar in which an avalanche breakdown is employed, which is triggered at low temperatures in the semiconductor by impact ionization of dopant particles, as reported in the Proceedings of the IRE, 1959, pp. 1207-1213. Components of this type are used primarily as high-speed switches, as their switching time is less than 10.sup.-8 seconds, and also as generators of electronic oscillations in the GHz range. These components are two-terminal networks whose operating point, and thus also the frequency of the oscillations which they produce, is dependent upon their construction and upon the operating voltage connected thereto.
If, for example, the oscillating frequency in an oscillating circuit equipped with a Gunn element is to be changed, the operating voltage directly connected to the Gunn element must be modified. A further disadvantage of the known components of this type resides in the fact that they cannot be produced by the processes employed for the production of MIS components, and for this reason they are not suitable for construction in integrated circuits. It is desirable to achieve components having a negative differential resistance whose operating point is controlled not only by varying the operating voltage, but also by a further auxiliary voltage. In this case, the control by the auxiliary voltage is to be able to take place using as little power as possible. Furthermore, the component is to be able to be constructed together with other MIS components.